1. Field of the Invention
This invention relates to an aluminum alloy sheet with improved forming workability and a method for manufacturing same. More particularly, the present invention concerns a bakehardening type aluminum sheet suitable for use in canning, which is improved especially in forming workability, and a method for manufacturing same.
2. Description of the Prior Art
Generally, aluminum alloy materials are used in canning as can bodies, can ends and can tabs, of which the material for can bodies is required to have satisfactory properties in: (1) drawability and redrawability; (2) ironing workability; (3) resistance to scoring; (4) doming formability; (5) appearance; (6) necking formability; (7) flangeability; (8) deep drawability; (9) resistance to pressure; (10) column strength; and (11) resistance to corrosion.
In order to realize a weight reduction of a can by a reduction in thickness of aluminum sheet material, it is necessary to reduce a can wall thickness within a range which is free of problems concerning can strength including column strength and so forth. For this purpose, it is a paramount requisite to attain improvements: (1) in ironing workability; (2) in flangeability since a reduction in wall thickness will lower flangeability; (3) in rivet formability for enhancing the effect of a reduction in wall thickness as a can end material; and (4) in bending workability for increasing an effect as a tab material in the same way as the can end material.
Of the above-mentioned properties, improvements are necessary especially in flangeability and rivete formability which are essential properties in a forming operation involving local elongation in particular.